In severe cases, it produces violent diarrhoea within only a few days. The dangerous aspect of cholera is the vast loss of fluid that can occur in a short space of time. It's particularly dangerous in children in developing countries.
Cholera is not really a tropical disease, but it's related to standards of hygiene and the quality of drinking water.
Cholera is caused by a specific bacterium, Vibrio cholerae.
When an adequate quantity of the bacteria has passed into the stomach in food, they accumulate and begin to produce poisonous substances (toxins). It's the toxin that causes the symptoms of the disease.
The cholera toxin has the unpleasant ability to affect the cells of the gastrointestinal tract, so that the affected person doesn't just get ordinary diarrhoea but also starts to lose large quantities of fluid. It's this fluid loss that can be serious.Bacteria are excreted in faeces and if this comes into contact with drinking water, the bacteria can infect people. So, the bacteria need an opportunity to multiply in water or food before it actually constitutes a risk.
Bacteria can also spread to food, if people don't wash their hands thoroughly after using the toilet. The food prepared at the funeral of a cholera victim is a common source of secondary spread in Africa!
The disease can be spread through fish and shellfish from contaminated water. Shellfish filter large quantities of water and concentrate the bacteria.
The incubation period, from infection until the disease breaks out, is generally less than two days, although it can be as long as five days.
The infection is often a mild illness with ordinary diarrhoea, and it can even evolve without any symptoms at all. But the individual is still able to pass on the disease.How can you avoid infection?
- Only drink boiled water or water that has been sterilised or treated in another way. Hot coffee and tea, fizzy water and other uncontaminated bottled drinks are usually safe enough to drink.
- Boil unpasteurised milk before you drink it.
- Avoid ice cubes in drinks, unless you can be sure they were made from 'safe water'! Ice cream from doubtful sources may also be contaminated.
- Food must be properly prepared and still hot when it's served. If it's allowed to stand at room temperature for several hours other bacteria, such as Escherichia coli, may develop.
- Avoid raw fish and shellfish.
- Avoid raw fruit and vegetables, unless you peel it yourself.
- Be careful eating food from street stalls. If you have to eat this type of food, think carefully about its preparation. Make sure it doesn't contain anything that hasn't been properly prepared.